Merge pull request #13883 from nestjs/fix/nats-client-promise-13880

fix(microservices): hold nats client connection promise ref

Author: kamilmysliwiec

packages/microservices/client/client-nats.ts

@@ -18,6 +18,7 @@ let natsPackage = {} as any;
 export class ClientNats extends ClientProxy {
   protected readonly logger = new Logger(ClientNats.name);
   protected natsClient: Client;
+  protected clientConnectionPromise: Promise<Client>;
 
   constructor(protected readonly options: NatsOptions['options']) {
     super();
@@ -30,13 +31,15 @@ export class ClientNats extends ClientProxy {
   public async close() {
     await this.natsClient?.close();
     this.natsClient = null;
+    this.clientConnectionPromise = null;
   }
 
   public async connect(): Promise<any> {
-    if (this.natsClient) {
-      return this.natsClient;
+    if (this.clientConnectionPromise) {
+      return this.clientConnectionPromise;
     }
-    this.natsClient = await this.createClient();
+    this.clientConnectionPromise = this.createClient();
+    this.natsClient = await this.clientConnectionPromise;
     this.handleStatusUpdates(this.natsClient);
     return this.natsClient;
   }

packages/microservices/test/client/client-nats.spec.ts

@@ -253,6 +253,7 @@ describe('ClientNats', () => {
     describe('when is not connected', () => {
       beforeEach(async () => {
         client['natsClient'] = null;
+        client['clientConnectionPromise'] = null;
         await client.connect();
       });
       it('should call "handleStatusUpdatesSpy" once', async () => {